Mar 9th 2011 2:37PM Exercise on the back does not significantly reduce uterine arterial blood flow. This has been established by top researchers in the field of maternal exercise physiology, most notable, Dr. James Clapp.
Additionally, only about 9% percent of all pregnant women experience true Supine Hypotensive Disorder (suppression of the Vena Cava when lying on the back) according to ACE, the American Council on Exercise. So for 91% of pregnant women, exercise on the back is safe.
And since the onset of Supine Hypotensive Disorder is quick, with sudden acute dizziness, it's very easy to detect. Because simply moving out of the supine position immediately eliminates the problem, Supine Hypotensive Disorder does not cause any lasting harm to the mother or her developing baby.
RE: The tendons that hold joints together... ligaments hold joints together, not tendons.
Apr 28th 2010 2:52PM Because the hormones of pregnancy length ligaments, especially in the last 20 weeks, pregnant runners should avoid running downhill which dramatically increases stresses on the anterior cruciate ligament of the knees.
Additionally, all pregnant women with a history of ankle sprains should never run on uneven surfaces as ligament laxity greatly increases the risk of a subsequent sprain.